Wearable audio device

Abstract

A wearable audio device with a magnetic field sensor that is constructed and arranged to sense the Earth's magnetic field. A magnet in the earphone, for example the magnet of the electro-acoustic transducer, produces a first magnetic field having a first magnetic field strength. A nulling magnet produces a nulling magnetic field along at least a first nulling magnet axis. The nulling magnet is configured to reduce an influence of the first magnetic field on the magnetic field sensor. The first nulling magnet axis, the first magnet axis, and the first sense axis are aligned.

What is claimed is: 
     
       1. A wearable audio device, comprising:
 a multiple-axis magnetometer that is constructed and arranged to sense the Earth's magnetic field along at least a first and second mutually orthogonal sense axes; 
 a first magnet that produces a first magnetic field along at least first and second mutually orthogonal first magnet axes; and 
 a nulling magnet that produces a nulling magnetic field along at least a first and second mutually orthogonal nulling magnet axes, wherein the nulling magnet is configured to reduce an influence of the first magnetic field on the magnetometer; 
 wherein the first nulling magnet axis, the first magnet axis, and the first sense axis are aligned. 
 
     
     
       2. The wearable audio device of  claim 1 , wherein the first nulling magnet axis, the first magnet axis, and the first sense axis are coaxial, and wherein the second nulling magnet axis, the second first magnet axis, and the second sense axis are coaxial. 
     
     
       3. The wearable audio device of  claim 1 , wherein the nulling magnet comprises a permanent magnet. 
     
     
       4. The wearable audio device of  claim 1 , wherein the first magnet comprises a transducer magnet of an electro-acoustic transducer that is adapted to create an audio output. 
     
     
       5. The wearable audio device of  claim 4 , further comprising a housing that is constructed and arranged to direct the audio output at the ear canal of the ear. 
     
     
       6. The wearable audio device of  claim 5 , wherein the nulling magnet is positioned in the housing such that the nulling magnetic field reduces the strength of the transducer magnetic field at the magnetometer. 
     
     
       7. The wearable audio device of  claim 1 , comprising an earbud with an earbud body, and wherein the magnetometer, the first magnet, and the nulling magnet are all located in the earbud body. 
     
     
       8. The wearable audio device of  claim 1 , wherein the magnetometer has a sensed magnetic field range where it operates linearly, and wherein the nulling magnetic field reduces the strength of the first magnetic field at the magnetometer such that the sensed magnetic field strength is in the sensed magnetic field range where the magnetometer operates linearly. 
     
     
       9. The wearable audio device of  claim 1 , wherein the first magnetic field has a direction along the first magnet axis, wherein the nulling magnetic field has an opposite direction along the first nulling magnet axis. 
     
     
       10. The wearable audio device of  claim 1 , wherein the first magnetic field has a direction along the first magnet axis, wherein the nulling magnetic field has the same direction along the first nulling magnet axis. 
     
     
       11. The wearable audio device of  claim 1 , wherein the magnetometer, the first magnet, and the nulling magnet are positioned along a common axis. 
     
     
       12. A wearable audio device, comprising:
 a housing that is configured to be located at least in part in an ear of a user; 
 an electro-acoustic transducer in the housing for creating audio output that is provided to an ear canal of the user, the electro-acoustic transducer comprising a transducer magnet that produces a transducer magnetic field having a transducer magnetic field strength along at least a first transducer magnet axis; and: 
 a magnetometer in the housing and that is constructed and arranged to sense the Earth's magnetic field along at least a first sense axis; and 
 a nulling magnet in the housing and that is constructed and arranged to produce a nulling magnetic field along at least a first nulling magnet axis, wherein the nulling magnet is configured to reduce the strength of the transducer magnetic field along the first transducer magnet axis at the magnetometer; 
 wherein the first transducer magnet axis, and-the first sense axis, and the first nulling magnet axis are aligned. 
 
     
     
       13. The wearable audio device of  claim 12 , wherein the magnetometer has a sensed magnetic field range where it operates linearly, and wherein the transducer magnetic field at the magnetometer has a strength such that the sensed magnetic field strength is in the sensed magnetic field range where the magnetometer operates linearly. 
     
     
       14. The wearable audio device of  claim 12 , wherein the magnetometer is constructed and. arranged to sense the Earth's magnetic field along at least first and second mutually orthogonal sense axes, wherein the transducer magnetic field has first and second mutually orthogonal first transducer axes, wherein the nulling magnetic field has first and second mutually orthogonal nulling magnet axes, and wherein the second nulling magnet axis, the second transducer magnet axis, and the second sense axis are aligned. 
     
     
       15. The wearable audio device of  claim 12 , wherein the transducer magnetic field has a direction along the transducer magnet axis, wherein the nulling magnetic field has an opposite direction along the first nulling magnet axis. 
     
     
       16. The wearable audio device of  claim 12 , wherein the transducer magnetic field has a direction along the transducer magnet axis, wherein the nulling magnetic field has the same direction along the first nulling magnet axis.